This invention relates to a method and apparatus for disposal of weft yarn in a shuttleless loom such as an air jet loom or water jet loom.
Towards realizing higher speeds in the weaving operation, air or water jet looms are employed wherein measured lengths of the weft yarn are inserted into the shed defined between upper and lower warp yarns. In these high-speed looms, the effect of interruptions of loom operation on the productivity or operating efficiency is more pronounced than in conventional looms. Hence it is preferred that the time interval of these interruptions or machine dwell time be as short as possible. On the other hand, jet looms are more susceptible to weft inserting failure than in shuttle looms because the weft yarn is carried through the shed by air or water and thus without resorting to shuttles. Hence, there may occur a supply failure, that is, the weft not being supplied from the supply jet nozzle, or a transfer failure, that is, the weft yarn not reaching the selvage yarn opposite to the jet nozzle.
In a jet loom operating at an elevated speed, the operational timing is so selected that although the drive system of the loom is deactivated upon detection of a weft inserting failure in order to avoid possible troubles due to excessive deceleration, the movable parts of the loom are halted only after about one cycle of inertial operation subsequent to the detection of the weft inserting failure. The result is that, in cases where the jet loom is stopped responsive to the inserting failure signals, the weaving cycle next to the cycle during which the inserting failure is occurred is executed before the machine is actually at a standstill. Hence, not only does the waft yarn fail to reach the opposite selvage, but also the next following weft yarn needs to be removed through the reversal of the loom operation. However, it is extremely difficult to remove the weft yarn inserted directly after the occurrence of the inserting error because it is already beated up as the other weft yarns and thus held firmly in the cloth. In addition, since the jet nozzle side end of the weft yarn failing to reach the opposite selvage is cut short, it is extremely difficult to hold this yarn end. The result is that the weft yarn failing to reach the opposite selvage can be removed only by an extremely difficult and troublesome operation. In addition, in order to carry out the correction of the inserting error and to restart the loom, it is necessary to operate the various movable parts of the loom for reversing the loom operation in accordance with a complicated operational procedure. This requires considerable skill.
On the other hand, in cases where the warp yarns including the selvage yarns are broken during weaving, or where the main switch of the loom is turned off through human intervention, the loom is halted after an inertial operation continuing for about one weaving cycle, for the reason discussed above. The weft yarn inserted during this inertial operation also has to be removed, if it is desired to obtain a woven cloth free of the weaving bar or the like defects. However, it is extremely difficult to remove the weft yarn once inserted during this inertial operation, as discussed above in connection with weft inserting failure.
Accordingly, there was a need for the method and apparatus for disposal of weft yarn in case of occurrence of weft inserting failure or warp breakage in a jet loom, by means of which the jet loom halted through weft inserting failure, warp breakage or human intervention can be readied for restarting easily and without requiring operational skill.